I generally view data sheets as a sales tool from the manufacturer. They sometimes differ from what is in the product manual. If you look at the inverter manual, usually near the end you'll find the technical specifications and reference to the UL or other agency listing for the product, sometime even a copy of the listing letter. I've seen this with SMA. The specs and the listing information typically specify the maximum OCPD device rating. I believe supplying an OCPD that meets that requirement is necessary for the listing to be valid. Without a valid listing, your installation would not be NEC compliant.
Jeff Irish Hudson Solar -----Original Message----- From: RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Richard L Ratico Sent: Friday, June 27, 2014 6:53 AM To: re-wrenches@lists.re-wrenches.org Subject: Re: [RE-wrenches] Combining Multiple Inverters I may be playing devil's advocate here, but I want to add a few thoughts. Jay, I just looked at Fronius and SMA inverter data sheets. I found no spec. for an output OCPD, only a spec for max. output current. William, most inverters now come with integrated DC/AC discos. Dave, 2014 NEC 705.12(D)(1), IMHO, specifies ONE OCPD for the entire interconnected power system, not individual OCPD for each inverter. Generally speaking OCPD is provided for the circuit conductors in a system, not the individual pieces of equipment. If the equipment manu. specifies OCPD, that is a different story. I understand the 2014 code to require appropiate OCPD for all the conductors from the panelboard to the inverter. If that can be accomlished with one device at the panel, it meets code. That said, code is a MINIMUM standard. Bottom line, I agree with Corey that there is no code requirement for individual OCPD for each inverter. If there is, unfortunately, it is insufficiently explicit such that we are having this conversation. Dick Ratico Solarwind Electric --- You wrote: I have never seen an inverter that does not specify a OCPD size. Jay Peltz power. Sent from my iPhone > On Jun 26, 2014, at 3:20 PM, Dave Click <davecl...@fsec.ucf.edu> wrote: > > Corey, > > The line of reasoning is faulty. It's 705.12(D)(1). Micro-inverters > are the exception because they are specially listed to share a breaker. As for the other inverters, doubling them up on a single breaker / disconnect probably goes against their installation instructions [110.3(B)] and it's unlikely that you could put multiple units on a single breaker anyway because when you take (2 inverters) x (rated current) x (1.25) you will probably come up with a minimum breaker size that is larger than the maximum allowed under the NRTL listing to UL 1741. > > Dave > > > >> On 2014/6/26, 16:18, Corey Shalanski wrote: >> We considered the necessity to shut down individual inverters and >> determined that the added costs of an inverter output combiner panel were not merited. I agree that in theory it seems beneficial to be able to switch each inverter individually, but how often does this occur in practice? For the relatively infrequent cases where we need to return to a jobsite and shut down an inverter - for troubleshooting/removal/etc. - we do not mind shutting down the other inverters (up to a limit) for what is hopefully a short period of time. >> >> Again, this whole line of reasoning may be shown to be faulty if >> someone can directly point to the Code section that requires OCPD on each individual inverter. >> >> -- >> Corey >> $E1eB >> >> >>> On Thu, Jun 26, 2014 at 9:20 AM, >>> <re-wrenches-requ...@lists.re-wrenches.org> wrote: >>> >>> Message: 5 >>> Date: Wed, 25 Jun 2014 19:17:57 -0700 >>> From: William Miller <will...@millersolar.com> >>> To: RE-wrenches <re-wrenches@lists.re-wrenches.org> >>> Subject: Re: [RE-wrenches] Combining Multiple Inverters >>> Message-ID: <04f4b8fd-e280-4bf2-b5a4-c2fca8d1c...@millersolar.com> >>> Content-Type: text/plain; charset="utf-8" >>> >>> Not allowed. You need a dedicated OCPD. Plus seems like a really bad idea. How do you shut down just one inverter? >>> >>> >>> >>> Miller Solar --- end of quote --- _______________________________________________ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org _______________________________________________ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org
